Antibodies to quinolinic acid reveal localization in select immune cells rather than neurons or astroglia.

Polyclonal antibodies were produced against quinolinic acid. No immunoreactivity was observed in any cell type in carbodiimide-fixed brain tissue from control rats. When the antibodies were applied to carbodiimide-fixed spleen tissue, strong quinolinic acid immunoreactivity was observed in some cells with the appearance of macrophages and dendritic cells. These findings indicate an immune system origin for quinolinic acid, and implicate immune cells in excitotoxic CNS pathologies. These findings also raise the possibility that quinolinic acid is a unique cytokine in immune system signal transmission.